1. Field of the Invention
This invention relates to an apparatus for facilitating assembling of a covering sheet onto a cushioned padding for a seat and, more particularly, to an apparatus which facilitates fastening of a covering sheet to a cushioned padding using tensioning cords, and facilitates covering of the cushioned padding with the covering sheet.
2. Description of the Prior Art
Referring now to FIGS. 1 to 4, a conventional method for assembling a covering sheet onto a cushioned padding for, e.g., a seat back of a vehicle seat will be discussed hereinafter in order to facilitate understanding of this invention.
As shown in FIG. 1, a first piece c1 of covering material, two second pieces c2 of covering material (only one second piece is shown in FIG. 1), and two third pieces c3 of covering material are sewed together using a needle, whereby a covering sheet C which has a three-dimensional shape and which is opened at a rear side of the three-dimensional covering sheet is prepared. A cushioned padding P has a central portion p1 corresponding to a portion of a finished seat back against which a person rests when the person sits on a finished seat having the seat back, bulged portions p2, p3 formed at left and right side portions of the central portion p1, and a cavity (not shown) formed in a back side of the cushioned padding P, in which a seat back frame is to be assembled. The first piece c1 of the covering sheet C is to cover the central portion p1 of the cushioned padding P, the second pieces c2 of the covering sheet C are to cover the bulged portions p2, p3 of the cushioned padding, and the third pieces c3 of the covering sheet C are to cover the back side of the cushioned padding P. The three-dimensional covering sheet C has vertically and horizontally extending tensioning cords (not shown) provided in an interior of the covering sheet C. The central portion p1 of the cushioned padding P has vertically and horizontally extending grooves g1, g2, g3, g4 formed in a surface thereof. As will be discussed in greater detail hereinafter, the vertically and horizontally extending tensioning cords which are provided in the three-dimensional covering sheet C are to be received in the grooves g1, g2, g3, g4 of the cushioned padding P and are to be fastened to the cushioned padding P.
Referring to FIG. 2, fastening of the covering sheet C to the cushioned padding P is performed by causing the covering sheet C to be turned inside out, manually pulling the tensioning cords r1, r2 of the covering sheet C, causing the tensioning cords r1, r2 to be received in the grooves g1, g2 of the cushioned padding P by hand, and fastening the tensioning cords r1, r2 to the cushioned padding P by C-rings which are to be shot into the grooves g1, g2 by a handy gun H. More particularly, as best shown in FIG. 3, the cushioned padding P has insert wires W (only one insert wire W is shown in FIG. 3) which are previously provided in the cushioned padding P in a state where they are exposed to the grooves from the cushioned padding P. The fastening of the covering sheet C to the cushioned padding P is carried out by shooting the C-ring E from the handy gun H into the groove r1 in such a manner that the C-ring E is twined round the insert wire W. However, in such a manual method, it is hard to cause the tensioning cords to be received in the grooves of the cushioned padding and fasten the tensioning cords to the cushioned padding, because the grooves are formed deeply in the cushioned padding, particularly, the vertically extending grooves g1, g2 formed in portions of the cushioned padding P which are adjacent the bulged portions p2, p3 are deep. Therefore, there is a possibility that the tensioning cords will be easily separated from the cushioned padding.
After the fastening of the tensioning cords to the cushioned padding P, as shown in FIG. 4, covering of the cushioned padding P with the covering sheet C is performed by manually pulling the covering sheet C while causing the right side of the covering sheet C to be out. At this time, high-tension is applied to the covering sheet from the cushioned padding. The tension is intensively applied to sewed portions of the pieces making up the covering sheet, so that the sewed portions of the covering sheet C are pulled away from each other so as to be opened, and holes which were provided in the covering sheet C by the needle, when the pieces making up the covering sheet were sewed together using the needle, are exposed. This detracts from an appearance of a finished product.